Re: Intentional Corruption

Hi,

Disclaimer: I'm not a lawyer and this is not a legal advice 8-) And please do not do this on your production system ;-)

Described approach should work if your datafiles are located on the filesystem and your system is a UNIX one

• calculate the offset in bytes for your table in the datafile by using dba_extents view and the fact that size of any datafile is one database block over the size reported in v$datafile (alternatively you can use DBMS_ROWID to corrupt a specific row)
• dd if=/dev/zero of=<datafile> bs=1 seek=<calculated offset> count=<number of bytes to corrupt> conv=notrunc (this syntax is for Solaris)
• in shell sync; sync; sync to make sure filesystem cache was flushed to disk.
• flush your db cache by using alter system flush buffer_cache
• do a full table scan

That should be enough to detect a corruption.

PS: you can experiment with <number of bytes to corrupt> or <calculated offset> to get desired result. Keep in mind that you should aim to corrupt the blocks below HWM of the target table in order for FTS to detect a corruption.

--romas

On 2/14/08, Ahbaid Gaffoor <ahbaid_at_att.net> wrote:
>
> Is there a way to intentionally introduce block level corruption?
>
> I'd like to play with some scenarios to learn more about DBMS_REPAIR
>
> thanks
>
> Ahbaid
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